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Title: Prediction of Precipitation Strengthening in the Commercial Mg Alloy AZ91 Using Dislocation Dynamics

Journal Article · · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science
 [1];  [2];  [2];  [3];  [3]
  1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
  2. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
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In this paper, dislocation dynamics simulations were used to predict the strengthening of a commercial magnesium alloy, AZ91, due to β-Mg17Al12 formed in the continuous precipitation mode. The precipitate distributions used in simulations were determined based on experimental characterization of the sizes, shapes, and number densities of the precipitates for 10-hour aging and 50-hour aging. For dislocations gliding on the basal plane, which is expected to be the dominant contributor to plastic deformation at room temperature, the critical resolved shear stress to bypass the precipitate distribution was 3.5 MPa for the 10-hour aged sample and 16.0 MPa for the 50-hour aged sample. The simulation results were compared to an analytical model of strengthening in this alloy, and the analytical model was found to predict critical resolved shear stresses that were approximately 30 pct lower. A model for the total yield strength was developed and compared with experiment for the 50-hour aged sample. Finally, the predicted yield strength, which included the precipitate strengthening contribution from the DD simulations, was 132.0 MPa, in good agreement with the measured yield strength of 141 MPa.

Research Organization:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Michigan, Ann Arbor, MI (United States); Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC52-07NA27344; SC0008637
OSTI ID:
1438644
Report Number(s):
LLNL-JRNL-734977; TRN: US1900474
Journal Information:
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 49, Issue 5; ISSN 1073-5623
Publisher:
ASM InternationalCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 13 works
Citation information provided by
Web of Science

References (24)

Investigation of precipitation hardening by dislocation dynamics simulations journal November 2006
Orowan process controlled dislocation glide in materials containing incoherent particles journal July 2001
Modeling the precipitation processes and strengthening mechanisms in a Mg-Al-(Zn) AZ91 alloy journal August 2005
Dynamic simulation of solution hardening journal October 1978
TEM study of continuous precipitation in Mg–9 wt%Al–1 wt%Zn alloy journal May 2000
Strain hardening behaviour and the Taylor factor of pure magnesium journal March 2008
Bauschinger effect in precipitation-strengthened materials: A dislocation dynamics investigation journal July 2009
Analysis of Obstacle Hardening Models Using Dislocation Dynamics: Application to Irradiation-Induced Defects journal May 2015
Dislocation movement through random arrays of obstacles journal October 1966
Orowan strengthening at low temperatures in bcc materials studied by dislocation dynamics simulations journal January 2011
Simulations of dislocation glide in overaged precipitation-hardened crystals journal April 2001
The effect of dislocation self-interaction on the orowan stress journal December 1973
The Influence of Al Content and Thickness on the Microstructure and Tensile Properties in High-Pressure Die Cast Magnesium Alloys journal January 2017
First-principles data for solid-solution strengthening of magnesium: From geometry and chemistry to properties journal October 2010
Dislocation motion in magnesium: a study by molecular statics and molecular dynamics journal August 2009
Orowan strengthening and forest hardening superposition examined by dislocation dynamics simulations journal October 2010
Superposition of dispersion strengthening and size-mismatch strengthening: Computer simulations journal January 2003
Comparison between dislocation dynamics model predictions and experiments in precipitation-strengthened Al–Li–Sc alloys journal October 2014
Age hardening in a Mg-9 wt.% Al alloy journal February 1968
Effective values of critical resolved shear stress for slip in polycrystalline magnesium and other hcp metals journal October 2010
Enabling strain hardening simulations with dislocation dynamics journal July 2007
Grain Size Hardening in Mg and Mg-Zn Solid Solutions journal January 2011
Results and consequences of a recalculation of the frank-read and the orowan stress journal May 1966
Dislocation Movement Through Random Arrays of Obstacles journal February 1967

Cited By (1)

Plastic flow anisotropy drives shear fracture journal February 2019

Figures / Tables (7)

Figure 1(p. 7)figure Figure 1
Table 1(p. 8)table Table 1
Figure 2(p. 12)figure Figure 2
Table 2(p. 12)table Table 2
Figure 3(p. 13)figure Figure 3
Table 3(p. 13)table Table 3
Table 4(p. 15)table Table 4

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